A suction catheter is used with an endotracheal tube for irrigating a patient's lungs to remove lung secretions. The suction catheter assembly includes a catheter surrounded by an elongated transparent flexible bag attached to an adapter for connection to the endotracheal tube. The opposite end of the catheter is connected to a suction machine or vacuum source by a suction control valve operated by a therapist or physician for selectively suctioning the patient. Examples of suction catheter assemblies are shown in U.S. Pat. Nos. 3,902,500, 5,125,893 and 3,991,762, the descriptions of which are incorporated herein by reference. In U.S. Pat. Nos. 4,569,344, 4,696,296, 4,836,199 and 4,872,579, there are disclosed suction catheter assemblies which include suction control valves by which an operator may selectively suction a patient as described in the aforesaid patents. However, such valves are costly to manufacture, assemble and maintain, and thus increase patient and hospital costs for procedures requiring the use of such apparatus.